EXPRESSION OF CYCLIC NUCLEOTIDE-GATED CATION CHANNELS IN NONSENSORY TISSUES AND CELLS

Using a combination of PCR based cloning and Northern blot analysis we have investigated the tissue expression of cyclic nucleotide-gated (C NG) cation channels in a variety of non-excitable tissues and cells. P artial sequences of all three known CNG channels and of an auxiliary s ubunit of the rod photoreceptor channel were determined. The expressio n of CNG channel genes is both tissue and species specific. Southern b lot analysis with human genomic DNA revealed specific patterns of hybr idization with probes derived from the different CNG channel types ind icating that they are encoded by distinct genes. Analysis of human gen omic sequences showed that all three genes are derived from a common a ncestral gene and might have a similar gene structure. We were not abl e to identify additional genes encoding CNG channels. The CNG3 channel , which was originally cloned from bovine kidney may be expressed also in bovine cone photoreceptor cells. These data suggest that some of t he effects of cGMP in peripheral tissues and cells might involve the a ctivation of CNG channels.